1. Field of the Invention
This invention relates to a communication device for executing a procedure requested with other communication device and more particularly, to a communication device in which a firewall is placed between the communication device and other communication device.
2. Description of Related Art
Various types of an information processing device have a communication function with development of information technology. For example, in an office, personal computers, printers, etc. are connected to each other through a communication line such as, e.g., a LAN (Local Area Network), and respectively function as a communication device. The communication device such as describe above can communicate not only data but also programs. The programs are communicated according to, e.g., a protocol referred to as a RPC (Remote Procedure Call). The RPC is defined as a system for calling a function exerted in other CPU among a plurality of different CPU. A standardized communication processing of the RPC is defined with a document, i.e., RFC (Request For Comments) 1831, issued by the IETF (Internet Engineering Task Force) (see Japanese Patent Application Publication No. JA-2003-114,805).
With the RPC as described above, the CPU functions as a communication device which receives instruction for execution of a prescribed procedure from the other communication device (other CPU) according to the protocol of the RPC. This communication device executes the prescribed procedure, and returns the results to other communication device. As described above, the communication device requested to execute the procedure from other device is referred to as a server-side communication device.
On the other hand, other communication device requests the execution of the procedure and receives the result. The communication device of this type is referred to as a client-side communication device (see Japanese Patent Application Publication No. JA-2003-114,805). In contrast, there has existed as one type of the communication devices such as having a function for notifying other communication device of its own internal status via an email (see Japanese Patent No. JA-3120,349). According to the invention, Japanese Patent No. JA-3120,349, it is possible to communicate via emails to other communication device outside, i.e., the firewall.
However, the above described arts have problems as follows. That is, it has been generalized in these years that organization such as, e.g., an enterprise, places the firewall between and an internal network and an external network.
The firewall is, herein, defined as an network intermediate device for restricting passable kinds of data and protocol for the purpose of preventing the communication device in the internal network from being controlling from the external network.
In the meantime, the communication in which a prescribed proceeding is rendered to execute from the outside, such as, e.g., the communication in accordance with the above described RPC, generally cannot pass through the firewall. Therefore, the communication device and other communication device as described above cannot be connected through the external network, so that a scope of the communication has been limited to an inside of the device or of the internal network, such as, e.g., the communication among a plurality of the CPU as described in Japanese Patent Application Publication No. JA-2003-114,805.
As described above, there has been such a problem that the existence of the firewall prevents the communication in using the RPC. On the other hand, as described in Japanese Patent No. JA-3120,349, with the regular email, messages can be transmitted but the execution of the proceeding according to the protocol such as, e.g., the RPC or the like can not requested.